Making conical pins



' March 23 1926.

Patented Mar. 23, 1926.

UNITED STATES PATENT QFFI CE.

VALENTIN nnrr'rnmrn, or meonsran'r, GERMANY, ASSIGNOR TO nno'rsonn WERKEax'rmnonsnnnscmr, or BERLIN-WILMERSDORF, A CORPORATION OF GER- I MAKINGCON IGAL PINS.

Application filed February 14, 1924. Serial- No. 692,845.

To all whom it may concern:

Be it known that I, VALENTIN RETTERATH, a citizen of the GermanRepublic, residing at Ingolstadt, Bavaria, Germany, have in- 5 ventedcertain new and useful Improvements in Making Conical Pins, of which thefollowing is a specification.

This invention "relates to a novel process or method for making conicallike fastening pins, shafts and the like which are required to be of aslightly conical-like shape for securing structural parts together orfor ready fastening to machine parts.

The usual practice in the manufacture of b such conical-like articles isto turn down cylindrical blanks to the requisite taper or to form suchtaper-like articles from suitable blanks by forging or sw'agingoperations, and by subsequent smoothing by turning where extremeaccuracy of contour is essential. The manufacture of the taperorconical-like articles, especially pins of the small dimensions to whichthis invention particularly Trelates, according to these prior methodsis a rather expensive and uneconomical procedure on account of theexpensive tools, the time and the skill of labor required,

According to the present invention the small conical-like fastening pinsof the char acter herein considered may be manufactured in a much moresatisfactory manner and with substantially greater and marked economy ascompared with the prior methods. My invention resides generally intheproduction of .such fastening pins and the like without the necessityfor any turning andmilling operations or without the necessity for any.swaging or. forging operations, such articles being obtained directly inone operation from the small cylindrical blanks or rods. It consistsgenerally in subjecting such blanks to one or more simultaneous lateralswelling and expanding operations, by pressure exerted radially toenetrate. the blanks to gradually increasing depths axially alongcircumferentially spaced longitudinal lines throughout those portions ofthe blanks to be increased in transverse dimensions, and causing thelateral and radially outward flow of the displaced metal along the sidesof the resultant narrow and circumscribed grooves of graduallyincreasing depth in axial directions against abutment and conformationsurfaces disposed between the circumferentially spaced lines andcorresponding to the conformation of the article desired. The blanks arethereby expanded and caused to swell up to' the required transversedimensions of gradually increasing effect in axial directions by "thesingle radial pressing operation and with no substantial diminution ofthe peripheral area or contact surface or impairment of the lateralstrength of the resultant conical-like fastening pin, the resultantgrooves, though slightly increasing in depth and width from one end tothe other of the pin, being of such narrow and circumscribed proportionsas compared to the intermediate portions of the pinat any point that theperipheral area thereof with its contact surface is only slightlyreduced by this operation. This method incidentally results in the' newand improved article in that I the narrow and shallow grooves along theperiphery of the pins permits the lateral flow of the expanded or bulgedout metal therein when the pins are driven into cylindrical or conicalholes.

For practicing my invention I have de vised a special apparatusincluding radially disposed and opposed forming and expanding diepressing members having recessed surfaces of slightly larger diameterthan the cylindrical blanks and obliquely disposed to the axis of theblank and conforming to the conformation of the conical-like pinsdesired, together with narrow longitudinal forming and penetrating edgesforming interruptions of said conformation surfaces and obliquelydisposed to the axis in opposite directions to those of the formingsurfaces, and these penetrating and cutting edges are adapted to formalong circumferent-ially spaced lines on blank narrow and circumscribedgrooves to effect the lateral bulging or expansion of the metal to theperiphery thereof to a gradually increasing degree throughout thearticle.

For a better understanding of the invention, reference may be had to theaccompanying drawings forming a. part of this ends of the pin beingpreferably rounded off. Figs. 2 and 3 are front and side elevationsrespectively of a conical pin made according to the invention and havingfour longitudinal grooves pressed -therein. Fig. 4 shows the arrangementof the stamping members. Fig. 5 is an elevation partly in sectionillustrating the action of the stamping members upon a pin blank. Figs.6 and 7 are upper 'and lower plan views corresponding to the pin in Fig.5. Fig. 8 shows in side view a fitting pin 9 made by this arrangement;and Fig. 9 shows a double conical shaft constructed according to theinvention.

Referring to the drawings a plurality of radial stamping members or dies6 are employed of a height equal to the conical pin or the like tobemade. The members 6 are furnished with projecting ridges 8 which areadapted to press into the blank when a pressure is applied theretoradially, the material of the blank being thereby caused to.

move outwardly to fill the space between the dies and to form theconical fitting surfaces against the recessed surfaces 7 of the dies.

By reference to Figs. 5, 6 and 7 it is seen that the ridges 8 areinclined inwardly and the recessed surfaces 7 outwardly of the axis ofthe blank which thus remains circular at the1 lower end and taperstowards its upper en In Figs. 2 and 3 a pin having four grooves formedin this manner is shown, whilst in Fig. 9 a shaft having a doubleconical surface is shown. By this process the cylindrical blank isreadily pressed to shape and pins with conical surfaces produced with.

great ease and exactitude.

I claim:

1. The method of forming tapered fastening pins with elongated shallowgrooves, comprising subjecting a section of stock to limited deformingpressure, radially applied, in a manner to form the grooves axially ofthe pin and to progressively enlarge the diameter of the pin uniformlytoward one end without substantially diminishing the peripheral contactarea or the lateral strength of the stock.

2. The method of forming a tapered fastoning pin from a cylindricalblank, which comprises forming shallow grooves in the blank whichgrooves increase in depth toward onevend and are along circumferentiallyspaced longitudinal lines, by the application of limited pressureradially and simultaneously applied by a plurality of deforming members,the pressure bein only sufficient to form the grooves and t ereby shapethe pin to its taper form without substantially reducing the peripheralcontact area or the lateral strength of the blank.

3. The method of forming tapered fastening pins with shallow groovesextending lengthwise of the pin, comprising subjecting a length ofcylindrical stock to limited deforming pressure which is radiallyapplied and sufficient only to form shallow grooves of increasing widthand depth along circumferentially spaced longitudinal lines and tolaterally displace small quantities of metal from the. grooves towardthe periphery of the pin to give the tapered dimension Withoutsubstantially diminishing the peripheral contact area or the lateralstrength of the stock. y

In testimony whereof I have hereto affixed my signature.

VALENTIN RETTERATH.

